Modern humans are dimorphic as well. Not to the extent as many other species but, for example, male brains are slightly larger, even accounting for their larger body size vs female.This suggests that throughout humans and their ancestors have been moderately polygynous.

Technically, there are examples of animals using tools. The chimp using the stick to get at termites is the commonly cited one. They even show an ability to select the best stick to use, and modify it to some extent. However, there's a big difference between fishing out termites with a stick, or using a leg bone as a cudgel to challenge a competing tribe for domination of a watering hole, and making things like hand axes, shovels, or bowls. Humans make tools that require many complex steps, most tool users in nature just pick things up off the ground. It's not a binary situation; humans and animals are all on a continuum of technical skill and complexity. Relative distance is what distinguishes us.

Indeed, it is called sympatric speciation. One of the two central concepts on how species arise. The other is allopartic speciation. They different in that the former happens at the same place at the same time. The latter requires some form of geographic isolation, like a river valley. No reason to think that the lineage leading to humans wasn't subjected to this kind of speciation.

Crows have been observed to construct tools [nationalgeographic.com] as well. In fact, they fashion more complex tools than chimps. They've learned different designs by copying other birds, and they pass their tool-building knowledge down through the generations.

Tool construction and use is not a uniquely human trait, it's not even unique to primates.

It is known as the Aquatic Ape Theory. [wikipedia.org] The mainstream anthropological view is that it is not correct. I still think most objections would disappear if you postulate partially aquatic near fresh water lakes instead of 100% aquatic life in salt water. But still, intriguing as it is, and as much as I would like to believe it is correct, the AAH (they have demoted it from theory to hypothesis) is not the current mainstream view.

The other thing I'd like to have an atheist tell me is how they believe water got here initially, and more specifically, why the water cycle starts on some planets and not on others. From what I was reading a while back, water actually initially gets produced in a closed-circuit chemical reaction, with the three elements, hydrogen, oxygen, and carbon. Once it gets started, the loop can keep going as long as those three elements are all present; my question is, how did those three elements become present here on Earth, especially when oxygen in particular seems to be rare almost to the point of being entirely unique in the universe, from what I've seen?

Hydrogen is by far the most abundant chemical element in the Universe. Helium is second. Oxygen is third. Carbon is fourth. None of these are in any way scarce; I have no idea where you got the notion that there was a shortage of oxygen in the Universe. As for water, the solar system is full of the stuff; water vapour is present in the atmosphere of Venus, water ice is present at the Martian poles, and the outer solar system is practically made of ice. The only thing that's unusual about Earth is the presence of liquid water.

I think they have, actually. Of course, Desmond Morris (zoologist, rather than anthropologist) entertained the idea in the widely read

The Naked Ape

, but there's been other work in the same vein. At the end of the day, it's not entertained seriously because it's simply not credible--it doesn't hold up to serious criticism. You might start with http://www.aquaticape.org/ [aquaticape.org]

Yeah, this is ooold. Homo habilis's status as a species of Homo has been challenged many times before this. It has even been called Australopithecus habilis by some researchers. The views on the family tree of the human species are constantly changing, but AFAIK, Homo (?) habilis has for some time not been considered to be on the lineage that leads to us.

There are many instances in which dinosaurs are depicted in the artwork of early man. That dinosaurs and man existed at the same time is uncontestable. Their bones are found in the same layers, and their footprints side by side in the same mud. It's just the way it is.